For example, in the process of manufacturing semiconductor devices, a so-called photolithography technique is used to form a resist pattern as a mask for forming a predetermined pattern. According to a photolithography technique, a resist liquid is applied onto the surface of a semiconductor wafer (which will be referred to as “wafer”) to form a resist film. Then, the wafer with the resist film formed thereon is subjected to a light exposure process in accordance with a predetermined pattern. Then, the wafer with the light-exposed pattern formed on the resist film is subjected to a developing process.
In the developing process used as one of the steps of the photolithography technique, a developing solution is supplied onto the wafer to form a developing solution puddle all over the surface. Then, this state is held for a predetermined time to promote the developing process by natural convection. Thereafter, the developing solution is thrown off, and purified water is then supplied as a cleaning liquid to wash out the developing solution remaining on the wafer. Then, the wafer is rotated at a high speed to throw off the developing solution and cleaning liquid remaining on the wafer, thereby drying the wafer.
In recent years, semiconductor devices are increasingly miniaturized with advances in light exposure techniques and so forth, and thus resist patterns with a smaller size and a higher aspect ratio have come into use. Accordingly, a problem arises such that resist patterns are pulled and bent by a surface tension of a rinsing liquid, i.e., so-called “pattern fall” is caused, when the rinsing liquid is being removed from gaps between the patterns during a step of throwing-off and drying at the end of the developing step described above.
As a technique to solve this problem, Patent Document 1 discloses a proposed technique such that, for example, a surfactant solution is mixed into a rinsing liquid to decrease the surface tension of the rinsing liquid. Further, Patent Document 2 discloses a process in which a surfactant is supplied when a rinsing process is performed on a substrate after a developing process.
Unlike the conventional process using purified water, however, where a surfactant is used together with a rinsing liquid, the surfactant may generate particles and adversely affect the process or may cause pattern deformation. So far, optimum process conditions in light of these problems have not yet been found in a rinsing process using a surfactant.
[Patent Document 1] Jpn. Pat. Appln. KOKAI Publication No. 7-142349
[Patent Document 2] Jpn. Pat. Appln. KOKAI Publication No. 2001-5191